1. Field of the Invention
The present invention relates to a liquid crystal display (“LCD”) device and, more particularly, to a backlight unit including a structure in which the sensitivity of a light sensor for detecting color reproducibility of white light is increased, and an LCD device including the same.
2. Description of the Related Art
In general, a display device displays an image by converting data in an electrical format processed by an information processor of an electronic product into a visual image. These are various types of display devices such as a cathode ray tube (“CRT”), a plasma display panel (“PDP)”, a liquid crystal display (“LCD”), an electroluminescence (“EL”), and the like. The LCD device is a flat panel display device which displays an image using electrical and optical characteristics of a liquid crystal injected therein. Due to various advantages of the LCD device such as being thin in thickness, light in weight and low in power consumption as compared with other display devices, it is widely used in various industrial applications.
The LCD device is not a self-luminous display device. Therefore, it requires a backlight unit which emits light, as a separate light source. In general, the backlight unit uses a light source for generating white light, such as a cold cathode fluorescent lamp (“CCFL”), a flat fluorescent lamp (“FFL”), and the like. Recently, a light emitting diode (“LED”) is used to reduce power consumption and improve color reproducibility.
There are two types of LEDs such as a white light LED and a red, green, blue (“RGB”) LED. The RGB LED mixes light generated from red, green, and blue chips to generate white light. Since the life span of the red, green and blue chips of the RGB LED is different from one another and the RGB LED includes a brightness variation, the RGB LED detects the brightness of the white light using a light sensor to maintain the color reproducibility of the white light.
The light sensor detects the light of the RGB LED incident to a first surface of a light guide plate and emitted to a second surface of the light guide plate. When the light sensor is positioned on a sidewall of the second surface of the light guide plate, the thickness of the backlight unit is increased due to the thickness of the light sensor. Accordingly, the light sensor is arranged in a lower part of the second surface of the light guide plate.
The light sensor detects light emitted from the second surface of the light guide plate and reflected by a sidewall of a mold frame receiving the light guide plate. When the light guide plate is received in the mold frame, the distance between the light guide plate and the sidewall of the mold frame may vary according to manufacturing conditions. Moreover, when the light guide plate is in contact with the sidewall, the intensity of light reflected by the sidewall and emitted towards the light sensor may be reduced and thereby it is difficult for the light sensor to detect the brightness of light.